civetweb: fix warning

Signed-off-by: Sage Weil <sage@inktank.com>

diff --git a/src/civetweb b/src/civetweb
index f29f1d4996bcfa602c8da6f2bbe02186b7629373..041bebf7a3affe6700e72404dd159e35012b7990 160000 (submodule)
--- a/src/civetweb
+++ b/src/civetweb
@@ -1 +1 @@
-Subproject commit f29f1d4996bcfa602c8da6f2bbe02186b7629373
+Subproject commit 041bebf7a3affe6700e72404dd159e35012b7990